WASHINGTON — Since a deadly airline crash in 2009, the government hasn’t kept its promise to ensure that major airlines are holding their smaller partners to the same safety standards, a federal watchdog says.

The Transportation Department’s inspector general faults the Federal Aviation Administration for not taking steps to encourage the big airlines “to consistently share safety information and best practices” with regional airlines that operate flights under contract for them.

That business link is known as code-sharing, by which one airline sells tickets for seats on a flight operated by another airline — United and United Express, for example.

More than half of all airline flights in the U.S. are operated by regional airlines using names such as United Express, Delta Connection, American Connection and US Airways Express under code-sharing arrangements.

A flight operated by regional carrier Colgan Air for Continental Airlines under the name Continental Express crashed in February 2009 near Buffalo, N.Y., killing 50 people. After that crash, officials at the department and the FAA said they would begin reviewing code-share contracts to see if they impinged on safety.

Investigators cited pilot training lapses by Colgan as a factor. Colgan ended flying in September as part of its parent company’s restructuring.

A National Transportation Safety Board investigation and congressional hearings after the Colgan crash pointed out the differences in safety cultures that sometimes occur between the two types of airlines.

For example, at that time, some regional carriers were hiring pilots with as few as 250 hours of flight experience, which FAA rules allow. Major airlines typically hired pilots with about 10 times that much experience.

After the crash, pilot unions and safety advocates said regional carriers were driven to cut corners on safety, including hiring inexperienced pilots at low wages, in part to meet performance goals required under the code-sharing contracts.

Airlines that met their goals often earned more money under the agreements, while those that failed to meet such goals were sometimes penalized.

The FAA, despite earlier promises, isn’t reviewing any code-share contracts for their safety implications, and the Transportation Department reviews only a small share for their potential economic impact, not safety, the report said.

“As a result, most domestic code-share agreements go into effect without being reviewed by any (federal) regulatory entity,” the report said.

The Associated Press obtained a copy of the report before its public release.

The FAA also doesn’t have procedures in place “to advance the agency’s commitment to ensure the same level of safety between mainline air carriers and their code-share partners,” the report said.

Responding to the report, Robert Rivkin, the Transportation Department’s general counsel, said the FAA “believes that all carriers ... meet an appropriate level of safety” regardless of whether they are in a code-share agreement.

After the Colgan crash, Transportation Secretary Ray LaHood and then-FAA chief Randy Babbitt announced an industry-government “call to action” and they held a well-publicized safety summit.

An airline safety “action plan” released by FAA officials at the time promised that the FAA and the department would “develop the authority and processes to review agreements” between major carriers and their regional partners.

That plan said one of its short-term goals was that “major carriers should seek specific and concrete ways” to ensure that their smaller airline partner carriers adopt and implement the larger company’s most effective practices for safety. That was to include periodic meetings to review safety data gathering programs and “to constantly emphasize their shared safety philosophy.”

The inspector general’s report said that although the FAA sponsors biannual information-sharing events for the airline industry, “it has not taken steps to encourage mainline carriers to consistently share safety information and best practices with their code-share partners.”

The FAA dropped its plans to review code-sharing agreements because agency officials felt the largest airlines had taken steps to increase their safety sharing with their regional partners, the report said.

But the inspector general found that while that was true of one large airline, it wasn’t the case for others. The report reviewed four major and eight regional carriers who participate in code share agreements, but did not identify the airlines.

Rivkin replied in a letter to the inspector general that the FAA doesn’t make a distinction between “major” and “regional” carriers because “all of those carriers meet the same standards.”

Scott Maurer, whose 30-year-old daughter, Lorin, died in the Colgan crash, said he was disappointed but not surprised by the inspector general’s findings.

“These promises tend to end up becoming lip service,” he said. “It sounds good at the time, but there is no follow through.”

A year after the Colgan crash, then-Continental Airlines CEO Jeffrey Smisek angered victims’ families when he said it was the FAA’s responsibility to ensure Colgan’s pilots were properly trained, not Continental’s.

“We did not train those pilots. We did not maintain those aircraft. We did not operate the aircraft. But we expect them to be safe. We expect the Federal Aviation Administration to do its job,” Smisek told a hearing of the House Transportation and Infrastructure Committee.

The father of a law student killed in the crash later cornered Smisek in the hallway outside the hearing room, complaining that his daughter bought her ticket from Continental, not Colgan.

Smisek is now the president and CEO of the holding company for United Airlines, which merged with Continental.